Dr. Robert Califf, the acting commissioner and nominee to run the agency, announced the measures in a phone conference with reporters. He said the steps were an attempt by the agency to toughen its response to the crisis, in which tens of thousands of Americans were addicted to the prescription painkillers and were dying of overdoses. He said the actions were part of a broader government effort: Earlier this week, the Obama administration said it would ask Congress to spend an additional $1.1 billion next year on the problem, which would help increase badly needed treatment facilities.

“It has reached a point where we felt we had to step back and take a careful look at everything and see what we could do,” Dr. Califf said. “We thought we could do more.”

The decrees include convening an expert panel before approving some new opioids, strengthening requirements to study a drug after it has come to market, and increasing access to training on pain management for doctors and other prescribers.

Drug treatment experts welcomed the measures, but some said they were unlikely to change much.

“What I’m seeing here is the F.D.A. attempting to say something in response to congressional concerns, perhaps in response to the holdup of approval of the new F.D.A. commissioner, without actually having any vision for change,” said Dr. Nathaniel Katz, an assistant professor of anesthesia at Tufts University School of Medicine in Boston, whose company, Analgesic Solutions, develops treatments for pain.

Last month, Senator Edward Markey, Democrat of Massachusetts, became the latest lawmaker to block Dr. Califf’s nomination, over what he said was the agency’s limp response to the drug crisis. He said the department had “willfully blinded itself to the warning signs.”

Dr. Califf acknowledged that the broader concern from Congress had been noted at the agency.

“The level of concern is quite high from people in Congress,” he said. “This is an extraordinary situation.”

In a statement, Mr. Markey said the measures "fall short of what is needed," and said he would continue to block Dr. Califf’s candidacy.

The F.D.A. has come under fire for continuing to approve opioids. Hillary Clinton publicly condemned the agency’s decision in August to allow prescriptions of OxyContin, a powerful painkiller, for children. Its approval in 2013 of a drug called Zohydro brought public outcry over what critics saw as yet another opioid in a market flooded with them. “The F.D.A. has appeared to be somewhat nonchalant in their approach to the opioid epidemic,” said Dr. Carl R. Sullivan III, the director of the addictions program at West Virginia University.

But Dr. Sullivan, who has seen the opioid epidemic up close — West Virginia is among the hardest-hit states — said he saw the measures as a sign that the agency might be trying to shift course.

Some are steps addiction treatment specialists have long been asking for, like increasing the drugs studies after they come to market.

“I am hopeful,” he said.

A version of this article appears in print on , on Page A12 of the New York edition with the headline: Pressured on Opioids, F.D.A. Takes Steps to Toughen Stance. Order Reprints | Today’s Paper | Subscribe